Improbable healing in endodontics: a case series of favorable outcomes despite adverse prognostic conditions

Endodontic prognosis is based on clinical and radiographic factors that estimate the likelihood of treatment success. Because periapical healing reflects complex interactions among microbial, host, anatomical, and treatment-related factors, individual outcomes may occasionally differ from conventional prognostic expectations. This paper aimed to describe and critically analyze favorable outcomes in teeth presenting conditions traditionally associated with reduced probabilities of treatment success. Three clinical cases were described in accordance with the Preferred Reporting Items for Case Reports in Endodontics (PRICE) 2020 guidelines. The cases presented adverse prognostic conditions, including substantial root resorption, inability to achieve apical patency or complete canal instrumentation, overextension of root filling material, absence of a definitive coronal restoration, and lack of recommended periodontal treatment. Despite these conditions, the teeth remained functional and asymptomatic and demonstrated favorable radiographic outcomes during longitudinal follow-up. These cases illustrate that unfavorable prognostic conditions do not invariably result in treatment failure. The reported outcomes neither diminish the importance of established prognostic factors nor validate the treatment limitations encountered. Rather, they emphasize that prognosis is probabilistic and that unusual favorable outcomes should be interpreted cautiously as individual observations.